7 Common Causes of a Noisy Water Heater

Noisy Water Heater

Many homeowners experience a noisy water heater, and besides it being annoying, it could be an indication that there's something not working correctly. It's time well spent to diagnose the problem to prevent further damage, let alone, quiet things down. Here are 7 main reasons why you may have a noisy water heater.

What Causes a Noisy Water Heater?

Accumulation of Sediment & Mineral Deposits


If you hear a popping sound coming from your water heater there's a good chance you have sediment build-up within your tank.

Over time sediment will accumulate inside your tank. Performing regular maintenance on your water heater will help flush the build-up and keep your unit running efficiently.

Sediment is defined as any solid material that settles on the bottom of your water heater. It can enter your tank with the water supply in the form of sand or other debris, and it can also be minerals that are released as the water is heated. 

​Mineral deposit build-up is especially a problem in areas with hard water. Water absorbs minerals as it travels thru the ground. These minerals, primarily calcium and magnesium carbonate, are harmless from a health perspective. However, as the water is heated, these minerals separate from the water and form lime scale inside the tank.

The popping sound you hear can be caused by lime scale build-up. It can also be caused by the loose sediment floating at the bottom of your tank. Steam bubbles develop under the sediment and explode when the water is heated. The popping sound you hear is often the steam bubbles exploding!

When a water heater is not flushed on a regular basis, sediment will begin to build-up at the bottom. In some cases this can reach a point where flushing the tank will no longer be possible. 


As the water temperature rises the water within the tank expands, and begins to escape from under the sediment. The rumbling sound you hear is the water making its way thru the sediment.

If you are able to hear a rumbling sound, there's a good chance  that the sediment build-up has reached a critical level. Although, not dangerous, it is an indication that your water heater is not operating efficiently.

You should attempt to flush the sediment build-up from the tank. Be aware that this is a red flag that your tank may be prone to having future problems which may require you to replace it in the near future.​

Crackling, Sizzling, Hissing, or Popping

​If you own an electric water heater and you hear Crackling, Sizzling, Hissing, or Popping, there's a good chance that the sediment build-up has buried the lower heating element. 

When this happens, you should drain the tank and remove the heating element so that you can clean any sediment and lime scale build-up on the element.  Soak it  in vinegar and then gently use a wire brush. 

If you are unable to drain your water heater because the sediment build-up is clogging the drain valve, you many choose to wait until your tank begins to leak before purchasing a new water heater.

We highly recommend purchasing a water heater leak detector to prevent a huge mess. These devices will alert you when it detects water leaking from the tank, read our comprehensive article HERE

Restricted Water Flow


​A Sizzling sound is usually an indication that your water heater has restricted water flow. There are a few valves that can cause this irritating sound.

  • Check the T&P relief valve.​ This is a safety valve designed to allow water to escape if the tank ever builds up too much pressure. If the sizzling sound is coming from this valve, we recommend shutting down the water heater by turning off the power and water. Then contact a professional plumber.
  • Check the water inlet valve to ensure that it is fully opened. This is the water valve that allows the incoming water to enter the water heater. 
  • Check all of the other waterlines and valves, including the water outlet valve to make sure there are no kinks in the lines. Also check that the valves are fully opened.  

Water Pressure Fluctuations


A ticking sound is typically caused from pressure fluctuations within the plumbing. Frequently, water heaters use water inlet and outlet nipples with heat traps. These nipples are where the plumbing connects to the heater and they help improve the unit's efficiency. If you find that this is the source of the ticking, you can simply remove and replace them with a non-heat trap nipple. 

It's also possible that your noisy water heater could be a result from your plumbing pipes and not your water heater at all. As the pipes leave your water heater, they ​expand and contract as the water temperature warms and cools. 

As the pipes expand they could rub against the wood framing and loose straps, resulting in a ticking sound. Follow the sound and try to pinpoint where it is the loudest. Then secure the pipe tightly or install spacers to keep the pipes from moving.

Sometimes by simply reducing the water heater temperature by a few degrees you will reduce the pressure and eliminate the noise. ​

Leaks & Condensation


​If you have a gas hot water heater and you notice a sizzling sound when the burner is ON, there is a good chance that you have an issue with condensation. When condensation forms it can drip onto the burner components. When the burner is hot you'll hear a sizzling sound as the condensation drips.

​A noisy water heater can also be caused by a leak inside the heater. This sound usually occurs when the burner is OFF. 

Check your water heater for leaks, you may find a puddle nearby. In many cases a sizzling sound is cause for contacting a professional plumber. ​

Water Source


If your water supply has a high pH level and your water heater uses an aluminum anode rod you may hear a popping noise. 

A reaction called Aluminum Hydroxide occurs in water with a high pH level. This is very common in areas that have chlorine/chloramines in the water supply. ​Chlorine has a pH level of 11.7.

To quiet your noisy water heater, simply remove the aluminum sacrificial anode rod​ and replace it with one made with magnesium.

It's also a good idea to flush and de-scale your water heater as there will be an increased level of lime scale build-up within your tank. ​

Water Hammer

Knock or Hammer Sound

An especially annoying and noisy water heater sound is Water Hammer. It sounds like a knock or a hammer and it occurs when the water flowing thru your plumbing is abruptly shut off.

When the water flow was abruptly stopped it leaves the water no where to go. So it flows in reverse back to its original source, in this case, your water heater.

The sound you hear is called Water Hammer and although the sound did not originate from your water heater, it can be very destructive. ​

Water Hammer has the potential to not only cause a pipe to burst within your house, but it could also create serious issues with your water heater. There can be enough force within the pipes to cause the tank shell to expand, collapse a flue tube, and even deform the top of the tank.​

Installing a Water Hammer Arrestor can protect your plumbing and water heater. These devices absorb the shock wave  created when the flow of water abruptly ends. The water hammer arrestor is designed with an air chamber inside which absorbs the shock once the pressure reaches the device. 

Heating Element


Electric water heaters can sometimes create a humming noise. This can be caused by one of the two heating elements. 

The upper heating element can vibrate and hum when cold water flows into the tank. Although, annoying, this noise is generally not harmful to either the heating element or the water heater. 

Use an element wrench to tighten the heating element. This fix will usually make your noisy water heater quiet again!